The purpose of so-called diverter systems is to provide low pressure control over the well during the preliminary stages of drilling, and, for this purpose, the system includes a housing supported with its bore beneath the rotary table on the platform and having one or more side outlets from the bore for connection with drilling mud return lines on the platform. A diverter assembly comprising a tubular body adapted to be lowered into a supported position in the bore of the housing has a port aligned with each side outlet from the bore, and a spool having packing at its lower end is suspended from the body for lowering over the upper end of a conductor extending upwardly from the preventer stack as the body is landed in the bore of the housing. More particularly, the tubular body carries means which seals between it and the housing bore to confine flow within the body into the side outlets with flow normally returning to the rig mud system from which it may be recirculated into the drill string. Packers are adapted to be lowered into and landed in the diverter body to seal about a drill string extending downwardly from the rotary table and through the tubular body leading to the conductor, whereby the drilling fluid returns about the string can be "diverted" into overboard lines connected to the outlets in the housing with reservoirs on the platform.
In prior systems of this type, a packer extending from the diverter body closes around a mandrel and allows for some height adjustment depending on the height of the stack. More particularly, the length of the spool is such that it is able to accommodate some misalignment of the bores of the diverter assembly and stack, as may occur, for example, due to movement of the stack relative to the platform. However, larger and thus taller stacks, necessitating correspondingly shorter spools, make it difficult if not impossible to maintain this essentially fixed connection between the diverter assembly and stack. Also, when the stack is at a substantial depth below water level, the stack experiences even greater movement with respect to the platform. Furthermore, even if the connection is able to flex the required amount under these conditions, there is no way to disconnect and reconnect the lower end of the diverter assembly, as may be required under adverse weather conditions.
There is therefore a need for and the primary object of this invention is to provide apparatus for so connecting the diverter assembly and blowout preventer stack which is of such construction as to accommodate such movement of the stack regardless of its depth, and, more particularly, to provide apparatus of this type which is easily connected to or disconnected from the stack irrespective of the extend of misalignment of the bores of the diverter assembly and stack.